It's been already two weeks and I still remember the next morning waking up with a smile. I felt my girlfriend moving next to me and gave her a kiss. She woke up and asked me The Question:"What happenned last night"? I tried to suffocate a laugh and answered:"I think we had an orgy". She was in a semi shock state. " Oh my goodness" , "I can't remember anything". I got a bit upset by this and all the questions that followed after but eventually she liked what we did. " Now I feel free" she said. The night before we had been invited in a normal party with lots of friendly couples and loads of vodka. Chatting with some guy, we heard a loud cheer and turned my head looking at my girl kissing another girl in the mouth. At the time I felt that it was some kind of bet or a girly thing and didn't pay attention but a few moments later, that lady's husband approached me and invited us for a night at their place, asking persistently for my phone number. I saw his lady smiling at me and then I got the picture. Why not? After all I had always fantasized it and talked about it with my girl. We left the party with a bunch of people, heading to our place I noticed that the friendly couple were coming along the same way. My girlfriend was a bit drunk so I took the opportunity and asked them to come to our house for a last drink. When we got into the appartment there was an akward moment of silence for a minute but then I saw my girl getting it off with the other lady. I took off her blouse and trousers and the other guy did the same on his lady. Then the ladies started to touch each other and the other guy and I took also our clothes off. The girls decided to go to the shower and for a while I had the chance to talk to the guy. He was tall and white, he was as shocked and horny as I was. We both played with our cocks all the time. The girls beeing in the shower for quite some time we went to search for them. They were kissing and playing with each others pussies. They were both saved and you could see how horny they were from the size of their nipples touching each other.When they saw us they started laughing and sprayed water on us. They got out of the bathroom and all four of us headed for the living room. The girls lied on the couch and opened their legs opposite to us playing with their pussies.Then they started to lick each other and soon they went to 69. I was amased by their passion. The other lady's tongue was deep in my girlfriends pussy. I start licking my girl's ass and then fucked her while on her fours. The other guy was doind his lady also. I thought that I was starring in a porn movie and although I was as horny as hell, I could feel that I wasn't sattisfied with any position. I wanted to change all the time so as to try as many things as possible. We fucked our girls at the same time while they were kissing or licking each others pussys. You could here the moans and the squirting sounds of the two pussies. The other girl had massive tits and was playing with them while begging her guy to screw her hard. She had already come twice when my girl jumbed on me to finish. I went on hammering her on the couch while the couple was watching. After I finished on her whole body the other lady started to bj her guy till he came all over her face. As my girl was exausted, lying on the couch, I took the opportunity to chat with the other couple.They had the same fantasy for quite some time but never had the chance to fulfil it. We were all very tired but still horny. Seeing what had happenned and after a cigarette break we started again. This time it was more separate action than all together. The girls were very tired.I got the opportunity to see the guy hammering her lady from up close, in a different angle this time. At the end, after everyone decided to call it a day. I offered to put them up but they kindly refused. We exchanged phone numbers and after a while they left. That was my first real swinging experience that in my opinion, emancipated my girlfriend and upgraded our relationship to another level. We will remember it for a very long time.